X0202 4 2006-01-31 0 0001340744 Altus Pharmaceuticals Inc. ALTU 0001157334 WARBURG PINCUS PRIVATE EQUITY VIII L P 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 0001322709 Warburg Pincus Partners LLC 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 0001162870 WARBURG PINCUS LLC 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 0000929408 WARBURG PINCUS & CO 466 LEXINGTON AVENUE NEW YORK NY 10017 0 0 1 0 Common Stock 2006-01-31 4 C 0 3589246 A 3589246 D Series C Convertible Preferred Stock 0.00 2006-01-31 4 C 0 3589246 0.00 D 2004-05-21 2006-01-31 Common Stock 3589246 0 D Warrant 9.802 2006-01-31 4 C 0 717917 9.802 A 2004-05-21 2011-05-21 Common Stock 717917 717917 D This is the date of the closing of the Issuer's initial public offering. Includes dividends that had been accruing on the Series C Convertible Preferred Stock and which were paid out in 325,995 shares of common stock as of the date of the closing of the Issuer's intial public offering. All outstanding shares of the Issuer's Series C Convertible Preferred Stock converted to common stock at a rate of .4401933369 - to- 1 upon the completion of the Issuer's initial public offering. The stockholder is Warburg Pincus Private Equity VIII, L.P. ("WP VIII"). Warburg Pincus Partners, LLC ("WPP LLC"), a subsidiary of Warburg Pincus & Co. ("WP"), is the sole general partner of WP VIII. WP VIII is managed by Warburg Pincus LLC ("WP LLC"). The address of the Warburg Pincus entities is 466 Lexington Avenue, New York, New York 10017. Jonathan S. Leff and Stewart J. Hen, directors of the Company, are general partners of WP and managing directors and members of WP LLC. Messrs. Leff and Hen disclaim beneficial ownership of all shares held by the Warburg Pincus entities. Charles R. Kaye and Joseph P. Landy are Managing General Partners of WP and Managing Members of WP LLC and may be deemed to control the Warburg Pincus entities. Messrs. Kaye and Landy disclaim beneficial ownership of all shares held by the Warburg Pincus entities. Warrants were automatically adjusted on a basis of .4401933369 - to- 1 upon closing of the Issuer's public offering. The number of adjusted warrants reported are exercisable for common stock on a 1 for 1 basis. /s/ Scott Arenare 2006-02-01 Scott Arenare 2006-02-02 Scott Arenare 2006-02-02 Scott Arenare 2006-02-02